The Active-Matrix-LCD (AM-LCD), including Thin Film Transistor LCD (TFT-LCD) and Thin Film Diode LCD (TFD-LCD), is currently the major technology of the flat panel color video display. The conventional AM-LCD, especially TFT-LCD, has been widely used in lap-top computers and pocket color Tvs.
The active matrix of the conventional AM-LCD are deposited on the internal surface of the LCD cell substrate, using multi-mask steps vacuum technology. This kind of AM-LCD is named as Internal-Active-Matrix-LCD (IAM-LCD).
However, this conventional AM-LCD has some major limitations. For instances, use of IAM-LCD in large screen display (&gt;20") is difficult as its applicability is limited only to smaller display screen sizes. In addition, IAM-LCD is difficult to manufacture, because of high processing cost for active matrix and high capital equipment investment. Furthermore, screen display employing IAM-LCD usually demonstrates certain drawbacks such as low brightness and low efficiency due to the low transmittance of color filter, smaller aperture, and polarizers.
The above-mentioned limitations, however, can be overcome by having the active matrix deposited on, instead of the internal surface, the outside surface of LCD substrate. The resulting product is called Out-Active-Matrix LCD (OAM-LCD) which possesses a series of attractive features previously unavailable to IAM-LCD. Briefly, these features include: (1) OAM-LCD is feasible for the manufacture of large screen LCD (i.e., 20".about.1000"or more); (2) OAM-LCD is easier to make due to lower processing cost, simple manufacturing process and the use of screen printing technology which eliminates vacuum mask steps, rendering the product defect-free; (3) OAM-LCD can be used in both indoor and outdoor applications due to its high level of brightness and high contrast property under high ambient illumination even at direct sunlight; (4) OAM-LCD demonstrates a high level of efficiency as it uses larger apertures without the need of color filter arrays and polarizers; and (5) OAM-LCD can be used with screen made entirely of plastic which is safer and easier for handling, especially for large screen and super large screen display.
It is therefore an object of the invention to provide an Out-Active-matrix-LCD processing the above-described features suitably used for large screen display.